Road tunnels are a particularly dangerous environment. Not only do fires burn more violently in enclosed environments, as happened in the 1999 Mont Blanc tunnel disaster, the low lighting and confined reaction space mean accidents are more likely to happen. Authorities must, therefore, be easily and quickly alerted to accidents, breakdowns and equipment must be working at all time.
To manage this process Sweden has implemented camera surveillance systems on almost all large tunnels. The latest to gain this technology is on the Norra Länken (Northern Link), a motorway in Stockholm, Sweden, between Norrtull and Karlberg. Once complete, almost 500 cameras will monitor the entire tunnel and the surface road network. 
To implement the network, the Swedish authorities turned to ISG, a systems integrator and intelligent video analysis specialist, based in the southern coastal city of Höganäs.